Apparatus for producing elastomeric nonwoven laminates

ABSTRACT

An apparatus for producing an elastomeric nonwoven laminate including a plurality of elastomeric strands joined to a nonwoven web in a controlled distribution is provided. The apparatus includes an extruder for extruding a plurality of elastomeric strands onto a cooled surface of a rotating drum, which transports the strands in parallel alignment to a nip formed between two rollers rotating about parallel axis. The drum transfers the plurality of strands to the nip in a controlled distribution where it is bonded with the nonwoven. The apparatus also includes elements which automate the apparatus for creating the elastomeric nonwoven laminate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/123,649, filed May 20, 2008, now U.S. Pat. No. 7,695,583, which is adivisional of U.S. application Ser. No. 11/787,373, filed Apr. 17, 2007,now U.S. Pat. No. 7,389,804, which is a continuation of U.S. applicationSer. No. 10/836,944, filed Apr. 30, 2004, now U.S. Pat. No. 7,222,654,all of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a method and apparatus formanufacturing an elastomeric nonwoven laminate comprising a plurality ofelastomeric strands and nonwoven material. More particularly, thepresent invention relates to a method and apparatus for automating themanufacturing of an elastomeric nonwoven laminate comprising a pluralityof elastomeric strands and nonwoven material.

BACKGROUND OF THE INVENTION

Disposable fluid-handling articles are often produced on high-speedconverting lines using continuous webs of fabrics, films, foams,elastomerics, etc. Many of these articles preferably include anelastomeric region or component. Typically, the elastomeric component iscovered on at least one side, and preferably two sides, by a nonwoven.This combination of nonwoven and an elastomeric is referred tohereinafter as an elastomeric nonwoven laminate.

Elastomeric nonwoven laminates typically include an elastomeric bondedto a nonwoven. The elastomeric may include elastic film or elastomericstrands; however, elastomeric strands are generally preferred overelastic films since strands require less material and provideflexibility in arrangement and stretch properties. In one such laminate,a plurality of elastomeric strands is joined to a nonwoven while theplurality of strands is in a stretched condition so that when theelastomeric strands relax, the nonwoven gathers between the locationswhere it is bonded to the elastomeric strands forming corrugations. Theresulting laminate is stretchable to the extent that the corrugationsallow the elastomeric to elongate.

Elastomeric nonwoven laminates with elastomeric strands may be producedby extruding a plurality of heated filaments onto a conveyor or rollerwhere the filaments are cooled and transferred to a nonwoven.Alternatively, the plurality of strands may be unwound from a supplyroll and joined to a nonwoven. In either case, arranging the strandsuniformly on the nonwoven can be difficult. The elastomeric strands aretypically transferred to the nonwoven and bonded by passing thecombination through a nip formed between two rolls.

When using extruded strand elastomerics, there are many situations whichincrease the startup time for the process, increase the amount of wastedmaterial, or cause downtime for the process. For instance, in a typicalelastomeric extrusion process, a nozzle opening that emits the moltenelastomeric is larger than the actual size of the elastomeric strand.The molten strand is typically drawn such that the diameter of theelastomeric strand which ends up in the laminate structure is smallerthan the size of the initial elastomeric strand emitted. During startupand the initial extrusion however, the elastomeric strands will tend toslide on the conveyor or roller. Because there is little normal forceactive upon the strands, the strands will tend to slide upon theconveyor or roller. Until a sufficient length of elastomeric strand hasbeen emitted, the strand will typically continue to slide upon theconveyor or roller thereby increasing the startup time for the process.

Other problems include the transfer of the elastomeric strands to thenonwoven. Because the elastomeric strands are typically unsupported, thevibrations and speed of operation cause the strands to fall out ofalignment, overlap, entangle, and bundle with neighboring strands. Theunsupported strands can also break or stick to the conveyor and nottransfer to the nonwoven at all which results in downtime for theprocess.

In addition to the transfer of the elastomeric strands, broken strandscan also cause significant problems particularly if the strands aretensioned. If a strand breaks under tension, the strand will tend tosnap back a significant distance towards its origination such that thealignment of the strands is disturbed thereby causing much of theresulting laminate corresponding to the snap back area to be wasted.

Consequently, it would be beneficial to provide a method and apparatusfor producing an elastomeric nonwoven laminate that is capable ofplacing the plurality of continuous elastomeric strands in a controlleddistribution on the mating nonwoven. In addition, it would be beneficialto provide an apparatus capable of reducing the amount of startup timefor the threading of the elastomeric strands, capable of reducing themisalignment that strands under tension cause when they break, andcapable of automatically capturing and threading elastomeric strandsthat fail to transfer to the nonwoven.

SUMMARY OF THE INVENTION

The present invention provides an apparatus and method for producing anelastomeric nonwoven laminate including a plurality of elastomericstrands bonded to a nonwoven web in a controlled distribution. Theapparatus includes an extruder for extruding a plurality of elastomericstrands on a cooled surface of a drum, which conveys the plurality ofstrands to a transferring device. A first nonwoven having a firstbonding surface is supplied from a first nonwoven source to thetransferring device. The transferring device is positioned close to thecooled surface of the drum to receive the plurality of elastomericstrands while allowing for a minimal span of unsupported strands duringthe transfer. The first nonwoven passes through the transferring deviceat second velocity V2 such that the first bonding surface receives theelastomeric strands conveyed from the cooled surface of the drum atfirst velocity V1. The elastomeric strands are pre-strained prior tobeing attached to the first bonding surface because V2 is greater thanV1.

In one embodiment, the apparatus includes a startup device disposedadjacent to the drum. The calendaring device is adaptable for engagingor disengaging the cooled surface of the drum such that when thecalendaring device engages the cooled surface of the drum, the pluralityof elastomeric strands travel along the cooled surface of the drum atthe surface speed V₁ of the drum.

In another embodiment, the apparatus includes an idler roller positionedbetween the first nonwoven source and the transferring device adjacentto the cooled surface of the drum. The idler roller directs the firstbonding surface to make contact with the cooled surface of the drum sothat the first bonding surface removes strands from the cooled surfaceof the drum that inadvertently fail to transfer to the transferringdevice. This embodiment also includes a second nonwoven source supplyinga second nonwoven which has a second bonding surface to the transferringdevice. An adhesive source for applying adhesive to the second bondingsurface in advance of the transferring device is also included.

In another embodiment this apparatus may include a scraper positionedadjacent to the cooled surface of the drum. The scraper is adaptable forengaging the cooled surface of the drum to remove elastomeric strandsthat inadvertently fail to transfer to the transferring device.

In another embodiment, the apparatus includes a deflector devicedisposed adjacent to the cooled surface of the drum. The deflectordevice minimizes the snap back distance that elastomeric strands exhibitupon breaking.

In another embodiment, when the transferring device comprises a firstand second roller which form a first nip therebetween, the apparatusalso includes a third roller and a fourth roller forming a second niptherebetween. The third and fourth roller each have a surface speed V₃where V₃ is less than the surface speed V₂ of the first and secondrollers. A second nonwoven source supplying a second nonwoven to thethird roller is also included. The second nonwoven has a second bondingsurface which is directed to contact the first roller such that thesecond bonding surface removes strands from the first roller thatinadvertently fail to transfer to the elastomeric laminate. The secondbonding surface of the second nonwoven is directed to contact the firstroller by a plurality of rollers disposed between the second nonwovensource and the third roller. This embodiment also includes a secondadhesive source for applying adhesive to the second bonding surface inadvance of the second nip thereby joining the second nonwoven to theelastomeric laminate.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter that is regarded as thepresent invention, it is believed that the invention will be more fullyunderstood from the following description taken in conjunction with theaccompanying drawings. None of the drawings are necessarily to scale.

FIG. 1 is a schematic side elevation view of an apparatus for laminatinga nonwoven and a plurality of strands of elastomeric forming anelastomeric nonwoven laminate according to the present invention.

FIG. 1A is a schematic side elevation view of an alternative apparatusfor laminating a nonwoven and a plurality of strands of elastomericmaterial forming an elastomeric nonwoven laminate according to thepresent invention.

FIG. 2 is a schematic side elevation view of the apparatus in FIG. 1including features which reduce startup time.

FIG. 3 is a schematic side elevation view of an apparatus for laminatinga first nonwoven to a second nonwoven including features which enablethe first nonwoven to swipe the drum clean of residual elastomericstrands in advance of the transferring device and provide self threadingof the elastomeric strands.

FIG. 4 is a schematic side elevation view of the apparatus in FIG. 1including features for self threading of the elastomeric strands to thetransferring device.

FIG. 5 is a schematic side elevation view of the apparatus in FIG. 1illustrating the snap back of a broken elastomeric strand.

FIG. 6 is a schematic side elevation view of the apparatus of FIG. 1including features which minimize the snap back of broken elastomericstrands.

FIG. 6 a is a close up of the feature which minimizes the snap back ofthe broken elastomeric strand.

FIGS. 6 b and 6 c are plan views of laminate structures showing theeffect of snap back with and without the minimizing snap back feature.

FIG. 7 is an apparatus for laminating a second nonwoven to a laminatehaving a first nonwoven and a plurality of elastomeric strands includingfeatures which enable the second nonwoven to swipe a nip roller ofresidual elastomeric strands in advance of joining the second nonwovento the laminate.

FIG. 8 is a schematic side elevation view of the apparatus in FIG. 7including features which enable a first nonwoven to swipe a drum ofresidual elastomeric strands in advance of a first nip.

FIG. 9 a is a side view of the elastomeric nonwoven laminate produced onthe apparatus depicted in FIGS. 3 and 7-8.

FIG. 9 b is a cross sectional view of the elastomeric nonwoven laminatedepicted in FIG. 9 a.

DETAILED DESCRIPTION OF THE INVENTION

The method and apparatus of the present invention are designed toprovide a more consumer desirable elastomeric nonwoven laminate suitablefor use in a variety of articles including a disposable fluid-handlingarticle. The elastomeric nonwoven laminate comprises a nonwoven and anelastomeric composed from at least one layer of a plurality ofelastomeric strands and at least one layer of a nonwoven material. Themethod and apparatus are capable of efficiently producing an elastomericnonwoven laminate having a controlled distribution of elastomericstrands.

Definitions

The following terminology is used herein consistent with the plainmeaning of the terms with further details provided in the presentspecification.

“Live stretch” includes stretching elastic and bonding the stretchedelastic to a nonwoven. After bonding, the stretched elastic is releasedcausing it to contract, resulting in a “corrugated” nonwoven. Thecorrugated nonwoven can stretch as the corrugated portion is pulled toabout the point that the nonwoven reaches at least one original flatdimension.

“Continuous filaments” refers to strands of continuously formedpolymeric filaments. Such filaments are formed by extruding moltenmaterial through a die head having a certain type and arrangement ofcapillary holes therein.

“Controlled distribution” refers to a parallel arrangement of elasticstrands having no overlapping or bundles of strands where the variationin distance between the elastic strands from the point of extrusion tothe point of lamination is minimal.

A “converting facility” refers to any production equipment producing oneor more components of a disposable fluid-handling article that aresubsequently assembled into a finished disposable fluid-handlingarticle. It may also produce a finished disposable fluid-handlingarticle that is complete for use by a consumer.

An “elastic,” “elastomer” or “elastomeric” refers to polymers exhibitingelastic properties. They include any material that upon application of aforce to its relaxed, initial length can stretch or elongate to anelongated length more than 10% greater than its initial length and willsubstantially recover back to about its initial length upon release ofthe applied force.

An “extrusion apparatus” or “extruder” refers herein to any machinecapable of extruding a molten stream of material such as a polymericthrough one or more extrusion dies.

The term “extrude” or “extruding” refers herein to a process by which aheated elastomer is forced through one or more extrusion dies to form amolten stream of elastic that cools into a solid.

The term “molten stream” refers herein to a linear deposit of a heatedliquid material such as a polymeric exiting an extrusion apparatus. Thestream may include continuous filaments, discontinuous fibers, orcontinuous films of a polymeric material. When cooled, the molten streamforms an elastic strand.

The term “joined” herein encompasses configurations whereby a materialor component is secured directly or indirectly (by one or moreintermediate members) to another material or component. An example ofindirect joining is an adhesive. Direct bonding includes heat inconjunction with or alternatively pressure bonding. Joining may includeany means known in the art including, for example, adhesives, heatbonds, pressure bonds, ultrasonic bonds, and the like.

The term “nonwoven” refers herein to a material made from continuous(long) filaments (fibers) and/or discontinuous (short) filaments(fibers) by processes such as spunbonding, meltblowing, and the like.Nonwovens do not have a woven or knitted filament pattern.

Nonwovens are typically described as having a machine direction and across direction. The machine direction is the direction in which thenonwoven is manufactured. The cross direction is the directionperpendicular to the machine direction. Nonwovens are typically formedwith a machine direction that corresponds to the long or rolleddirection of fabrication. The machine direction is also the primarydirection of fiber orientation in the nonwoven.

Description

FIG. 1 shows a side view of an apparatus 100 according to the presentinvention for producing elastomeric nonwoven laminate 190. The apparatus100 includes a drum 110 rotating about an axis 114 and having a surfacespeed V₁. The drum 110 is glycol cooled to provide a cooled externalsurface 112. The temperature of the cooled external surface ismaintained between 0° C. and 5° C. For orientation purposes, the drum110 has a first quadrant 111 a between 12 o'clock and 3 o'clock, asecond quadrant 111 b between 3 o'clock and 6 o'clock, a third quadrant111 c between 6 o'clock and 9 o'clock, and a fourth quadrant 111 dbetween 9 o'clock and 12 o'clock. The upper half is represented by thefirst and fourth quadrant 111 a and 111 d, while the lower half isrepresented by the second and third quadrant 111 b and 111 c.

A drum, in accordance with the apparatus described herein, can be sizedto accommodate any size laminate or process set up. For instance alarger drum may be utilized for offline material production operationswhere the elastomeric nonwoven laminate is stored on a roll or in a boxfor future use. Smaller drum sizes may be required for online operationsincorporated upstream of a converting operation. For offline operations,the diameter of the drum may be approximately one meter or larger,whereas for online operations the diameter of the drum may beapproximately 0.5 meters or less. Similarly for offline operations, thewidth of the drum may be approximately one meter or larger whereas foronline operations the width of the drum may be limited to approximatelyone meter or less. The rotation of the drum can be powered by a variablespeed motor capable of ramping up or down depending on the operator'sdemand.

The apparatus 100 includes an extruder 120 for extruding a molten streamof elastomeric polymer. The extruder 120 extrudes the molten stream ofpolymer through a plurality of nozzles 122 forming a plurality ofelastomeric strands 23 that flow in parallel alignment onto the cooledsurface 112 of the rotating drum 110. Preferably, the elastomericstrands are extruded onto the cooled surface 112 of the drum 110 suchthat the distance between any two adjacent strands ranges between about1 mm and about 3 mm. More preferably, the distance between any twoadjacent strands is about 1.5 mm. The extruder 120 is mounted betweenthe first and fourth quadrants 111 a, 111 d and deposits the pluralityof strands 23 onto the cooled surface 112 of the drum 110 near 12:00o'clock.

The extruder 120 preferably includes a built in metering pump, valve andnozzle arrangement wherein the metering pump and valve are positioned inproximity to the nozzle in order to provide a controlled discharge ofpolymer. The controlled discharge of polymer ensures that an adequatesupply of polymer is supplied to the cooled surface of the drumparticularly during starts and stops. Excessive flow of polymer duringstops can cause localized heating of the cooled surface of the drumwhich can lead to polymer build up caused by the elastomeric strandssticking to the surface of the drum.

A transferring device 131 is mounted near the cooled surface 112 of thedrum 110 at the third quadrant 111 c. The transferring device maycomprise a single roller, a plurality of rollers, or any other deviceknown in the art for combining a plurality of elastomeric strands to anonwoven or woven web or combining a plurality of nonwovens or wovenwebs or any combination thereof.

For the embodiment shown in FIG. 1, the transferring device comprises afirst roller 130 and a second roller 132. The first and second rollers130, 132 rotate about two parallel axes forming a nip 134 therebetween,where each provides a surface speed V2. The surface speed V2 of each ofthe rollers is greater than the surface speed V1 of the drum.

The first roller 130 is positioned proximate to the cooled surface 112of the drum 110 to minimize the span 150 of unsupported strandstransferring from the cooled surface 112 of the drum 110 to the firstroller 130. Preferably, the first roller is positioned as close to thecooled surface of the drum as possible without actually making contact.The actual measured distance separating the two depends upon the sizesof the drum and the first roller. For instance, for a drum diameter of 1meter and a first roller diameter of 150 mm, the distance between thecooled surface 112 of the drum 110 and the first roller 130 can rangefrom approximately 0.5 mm to about 5 mm. The corresponding length of thespan 150 of unsupported strands can range from about 18 mm to about 75mm. For smaller size drums, the length of the span 150 of unsupportedstrands can be shorter. For instance, a 0.5 meter diameter drum with a150 mm first roller 130 can enable the first roller 130 to be positionedas close as 1 mm to the cooled surface 112 of the drum 110 and limit thelength of the span 150 of unsupported strands to about 22 mm.

The first roller 130 receives the plurality of strands 23 near thecooled surface 112 of the drum 110, minimizing the span 150 ofunsupported strands between the cooled surface 112 of the drum 110 andthe first roller 130. Preferably, the plurality of strands 23 transfersfrom the cooled surface 112 of the drum 110 to the first roller suchthat the strands are approximately tangent to both the cooled surface ofthe drum and the surface of the first roller 130 and the length of thespan 150 of unsupported elastomeric strands 23 is minimal, rangingbetween about 10 mm and about 200 mm. Preferably, the length of the span150 of unsupported elastomeric strands 23 during the transfer rangesbetween about 20 mm and about 50 mm. By minimizing the length of thespan of unsupported strands during the transfer, the elastomeric strandscan be transferred to the first roller in a controlled distributionwhere the distance measured between any two adjacent strands varies 30%or less from the point of extrusion to the point of lamination. Forinstance, if the original spacing at the extruder is set at 1 mm, thespacing between any two adjacent strands will range between 0.7 mm to1.3 mm.

For the embodiment shown in FIG. 1, a first nonwoven source 140 suppliesa first nonwoven 144 having a first bonding surface 143 to the secondroller 132 forming the nip 134 with the first roller 130. A firstadhesive source 142 positioned between the first nonwoven source 140 andthe second roller 132 applies adhesive to the first bonding surface 143.The first nonwoven 144 and the plurality of elastomeric strands 23 passbetween the nip 134 formed by the first and second rollers 130, 132forming the laminate. As mentioned previously, because V2 is greaterthan V1, the difference in velocity strains the plurality of elastomericstrands 23 at the nip. Once the strain is relieved from the strands,corrugations form in the nonwoven providing an elastomeric nonwovenlaminate 190.

Upon exiting the nip 134, the elastomeric nonwoven laminate 190 may beconveyed directly to a converting operation which manipulates thelaminate to form a component of a disposable absorbent article such asan elastic waist band, an elastic cuff or an elastic side panel.Alternatively, the elastomeric nonwoven laminate 190 may be joined witha second nonwoven or other material and stored on a roll or in a box forfuture use.

Alternatively, the transferring device 131 i may comprise a singleroller, e.g. the first roller 130 i, as shown in FIG. 1A which forms thelaminate structure. The first nonwoven 144 i is provided to the singleroller 130 i by the first nonwoven source 140 i. The first bondingsurface 143 i of the first nonwoven 144 i is provided with adhesive froman adhesive source 142 i. As the first bonding surface 143 i of thefirst nonwoven 144 i contacts the single roller 130 i, the tension onthe first nonwoven 144 i causes the first nonwoven 144 i to exert aforce against the single roller 130 i. The force exerted by the firstnonwoven 144 i is sufficient to combine the first nonwoven 144 i and theelastomeric strands 123 i thereby forming an elastomeric nonwovenlaminate 190 i. Also, the transferring device shown in FIG. 1A can beutilized in any of the following embodiments with the exception of theapparatuses shown in FIGS. 7 and 8.

When the extruder initially extrudes the elastomeric strands through theplurality of nozzles, the strands slip with respect to the cooledexternal surface of the drum. A startup device can be incorporated intothe apparatus such that the slippage between the strands and the cooledexternal surface of the drum is minimized. The startup device maycomprise a conveyor which contacts the cooled external surface of thedrum. Also the startup device may comprise any mechanism which causesone or more strands to move at the same speed as the surface speed ofthe drum V1.

For the embodiment shown in FIG. 2, the startup device 255 comprises acalender roll 256. The calendar roll 256 engages the cooled externalsurface 212 of the drum 210 during the initial startup of the apparatusuntil the strands 223 are long enough to avoid slipping.

Shortly after contacting the cooled external surface 212 of the drum210, the extruded strands 223 contact the calender roll 256. Thecalender roll 256, being engaged with the cooled external surface 212 ofthe drum 210, increases the friction between the strands 223 and thecooled external surface 212 of the drum 210 thereby discouragingslippage by the strands 223. The calender roll 256 engages the cooledexternal surface 212 of the drum 210 such that the strands 223 arecompelled to travel at the same speed as the surface speed of the drum210. After the strands 223 have reached a sufficient length, the strandswill begin to be pulled by the drum 210 and will no longer require theincrease in friction that the calender roll 256 provides. When thisoccurs, the calender roll 256 can be disengaged from the cooled externalsurface 212 of the drum 210.

Optionally, a scraper 258 can be incorporated into the apparatus 200 inorder to preclude the elastomeric strands 223 from winding around thecalendar roll 256. As the calender roll 256 applies force to theelastomeric strands 223 causing the strands 223 to travel at the samespeed as the surface speed of the drum 210, the elastomeric strands 223have the potential to leave the cooled external surface 212 of the drum210 and wind around the calender roll 256. Because the scraper 258engages the calender roll 256, the strands 223 are precluded fromfollowing the surface of the calender roll 256 and thereby windingaround the calender roll 256. The scraper 258 can be incorporated withany of the startup devices disclosed herein.

Conveying elastomeric strands from an extruder to a first roller via arotating drum is difficult to maintain over an extended period of timeas a result of build up on the drum caused by elastomeric strands havingthe tendency to break and stick to the surface of the drum therebyfailing to transfer to the transferring device. In addition, manualthreading of the elastomeric strands from the cooled surface of the drumto the transferring device is often required at startup since the lightweight of the elastomeric strands causes them to stick to the surface ofthe drum rather than automatically making the transfer onto thetransferring device. Consequently, an alternate embodiment is providedin FIG. 3 including an additional apparatus for maintaining thecleanliness of the drum during normal operation and automaticallythreading the strands to the transferring device during startup.

As shown in FIG. 3, an idler roller 370 is positioned between the firstnonwoven source 340 and the second roller 332, which is disposedadjacent to the second quadrant 311 b of the cooled surface 312 of thedrum 310. The idler roller 370 directs the first bonding surface 343 ofthe first nonwoven 344 to contact the cooled surface 312 of the drum 310in advance of reaching the second roller 332. By making contact with thecooled surface 312 of the drum 310, the first bonding surface 343 canremove elastomeric strands that stick to the cooled surface 312 of thedrum 310 and fail to transfer to the nip 334 formed by the first andsecond rollers 330, 332. Because the first nonwoven 344 is fed directlyinto the second roller 332, any strands 323 which were removed by thefirst bonding surface 343 are fed into the nip 334.

A second nonwoven source 360 provides a second nonwoven 324 to be joinedwith the first nonwoven 344 and the plurality of elastomeric strands 323in the nip 334. The second nonwoven 324 has a second bonding surface 325and is provided to the first roller 330 which forms the nip 334 with thesecond roller 332. An adhesive source 342 applies adhesive to the secondbonding surface 325 such that when the first and second nonwovens 321,324 pass between the nip 334 sandwiching the plurality of elastomericstrands 323 therebetween, a laminate 390 is formed.

At the nip 334, a first strain is produced on the elastomeric strands323 as a result of the elastomeric strands 323 being extended in themachine direction. The strain is induced due to the difference insurface speeds, V2 and V1, as discussed previously with regard toFIG. 1. The greater the speed differences between the first speed V1 andthe second speed V2, the greater the resulting strain. For the presentinvention, the difference in speed creates a strain on the plurality ofelastomeric strands 323 ranging from about 20% to about 500%.

In an alternative embodiment, the apparatus may incorporate a scraper465 which engages the cooled external surface 412 of the drum 410 asexemplified in FIG. 4. Any strands 423 which do not leave the cooledexternal surface 412 of the drum 410 in the proximity of the nip 434 areremoved from the cooled external surface 412 of the drum 410 by thescraper 465. The proximity of the first roller 430 and the second roller432 to the scraper 465 insures that once any strands 423 are removedfrom the cooled external surface 412 of the drum 410, the strands 423engage the first bonding surface 443 of the first nonwoven 444downstream of the adhesive source 442. Because the removed strandsengage the first bonding surface 422 of the first nonwoven 421downstream of the adhesive source 442, the strands are transported suchthat they go through the nip 434 and re-engage the first roller 430.

Another problem with the production of laminate structures utilizingextruded elastomeric is that if the strands 523 break, the strands 523tend to snap back a significant distance along the cooled surface 512 ofthe drum 510 as shown in FIG. 5. The snap back of the broken strandcauses alignment problems with the remaining strands along a significantportion of the snap back distance. The resultant laminate receiving thestrands within the snap back distance of the broken strands aretherefore wasted because of strand alignment issues. (See FIG. 6 c).

In order to minimize the amount of material lost because of thisbreakage, a deflector device can be installed as shown in FIG. 6. Adeflector plate 575 is disposed adjacent to external surface 512 of thedrum 510 proximate to the first roller 530. The deflector plate 575precludes the strands 523 from snapping back a significant distancealong the external surface 512 of the drum 510. As shown in FIG. 6 a,the broken strand 523 strikes the deflector plate 575 which minimizesthe distance the strand 523 can snap back. Because the snap backdistance of the strand is minimized, the amount of resultant laminatestructure that is scrapped is also minimized. As can be seen inexaggerated form in FIGS. 6 b and 6 c, the amount of scrappedelastomeric laminate is minimized with the utilization of the deflectorplate.

Note that the deflector plate 575 is merely an example of how tominimize the snap back of the elastomeric strands. The deflector devicecan be a roller which engages the cooled external surface 512 of thedrum 510. Conversely, if the deflector device is a roller, the rollermay be disengaged from the cooled external surface 512 of the drum 510.The deflector device may comprise any device well known in the art forsustaining elastomeric strands.

Another problem is the exposed adhesive on the first bonding surface ofthe first nonwoven. Because there is exposed adhesive on the resultingbi-laminate structure of a first nonwoven joined to a plurality ofstrands, any down stream converting operations are virtually impossible.Additionally, the resulting laminate structure is gathered which rendersthe resulting laminate structure difficult to roll wind. Consequently,it is preferred to cover the elastomeric strands that are exposed on thefirst bonding surface of the first nonwoven. Such covering may include aflexible release paper joined to the first bonding surface downstream ofthe nip or a second nonwoven which can be joined to the first nonwoveneither upstream or downstream of the nip.

As shown in FIG. 7, additional elements may be added to the apparatus ofFIG. 1 in order to maintain the cleanliness of the first roller andthereby preclude the strands from winding around the first roller whilealso placing a second nonwoven on the nonwoven laminate 790. As anexample, the apparatus 700 shows a second nonwoven source 760 whichprovides a second nonwoven 724 having a second bonding surface 725 to athird roller 733. A first plurality of rollers comprising a first idler772 and a first pivot roller 774, and a first series of rollers 776, arepositioned between the second nonwoven source 760 and the third roller733. The first idler 772 and the first pivot roller 774 direct thesecond bonding surface 725 of the second nonwoven 724 to make contactwith the first roller 730 downstream of the first nip 734 which isformed by the first roller 730 and the second roller 732. By makingcontact with the first roller 730, the second bonding surface 725 canremove elastomeric strands 723 that stick to the first roller 730 andfail to transfer or adhere to the first nonwoven 744 in the first nip734.

The first pivot roller 774 can be arranged to force the second nonwoven724 in a reverse direction near the first roller 730 causing any straystrands collected from the first roller 730 to expel from the secondbonding surface 725. The first pivot roller 774 is preferably smallhaving a diameter which is less than about 20 mm. In an alternateembodiment, the first pivot roller 774 can be replaced with a staticplate or sheet, however, a roller is preferred since a static plate orsheet can induce strain on the nonwoven causing necking.

From the first pivot roller 774, the second nonwoven 724 can be made toproceed to a first series of rollers 776. The first series of rollers776 are arranged relative to the first pivot roller 774 such that theangle 784 between second nonwoven 724 approaching the first pivot roller774 and the second nonwoven 724 departing the first pivot roller 774ranges from 0 degrees to 90 degrees. As shown in FIG. 7, the firstseries of rollers 776 directs the second nonwoven 724 first away fromthe first pivot roller 774 and then back to the third roller 733. Thefirst series of rollers 776 can also be arranged to direct the secondnonwoven 724 to a second adhesive applicator 762 applying an adhesive tothe second bonding surface 725 prior to passing through the second nip736 formed by the third and fourth rollers 733 and 735.

The third and fourth rollers 733, 735 are mounted downstream of thefirst nip 734 created by the first and second rollers 730, 732. Thethird and fourth rollers 733, 735 rotate about two parallel axes, whereeach provides a surface speed V3. The surface speed V3 of each of therollers is less than the surface speed V2 of the first and secondrollers 730, 732. Note that if V3 is equal to V1 (the surface speed ofthe drum 710), then the elastomeric strands 723 of the elastomericlaminate 790, prior to entering the second nip 736, are fully relaxed.However, if V3 is less than V2 but greater than V1, then the elastomericstrands 723 of the elastomeric laminate 790 are only partially relaxed.

The elastomeric laminate 790 passes beneath the first pivot roller 774so that any strands expelled from the second bonding surface 725 at thefirst pivot roller 774 can be recollected onto the elastomeric laminate790 prior to reaching the second nip 736. From the first nip 734 theelastomeric laminate 790 passes through the second nip 736 where theelastomeric laminate is joined to the second nonwoven 724.

In addition to the apparatus of FIG. 7 which has a cleaning mechanismfor the first roller, the apparatus may include additional elementsallowing for the cleaning of the drum as well. As shown in FIG. 8,apparatus 800 provides additional elements for the cleaning of the drum810. A second plurality of rollers comprising a second idler 870, asecond pivot roller 880, a second series of rollers 883 are positionedbetween the first nonwoven source 840 and the second roller 832. Thesecond idler 870 is disposed adjacent to the second quadrant 811 b ofthe cooled surface 812 of the drum 810. The second idler 870 directs thefirst bonding surface 843 of the first nonwoven 844 into contact withthe cooled surface 812 of the drum 810 in advance of reaching the secondroller 832. By making contact with the cooled surface 812 of the drum810, the first bonding surface 843 can remove elastomeric strands thatstick to the cooled surface 812 of the drum 810 failing to transfer tothe nip 834 formed by the first and second rollers 830, 832,respectively.

After removing stray strands from the cooled surface 812 of the drum810, the first nonwoven 844 can be made to proceed to a second pivotroller 880 located adjacent to the second roller 832 forming the firstnip 834, a select distance from the second idler 870. The second pivotroller 880 can be arranged to force the first nonwoven 844 in a reversedirection near the second roller 832 causing any stray strands collectedfrom the cooled surface 812 of the drum 810 to expel from the firstbonding surface 843. The second pivot roller 880 is preferably smallhaving a diameter which is less than about 20 mm. In an alternateembodiment, the second pivot roller 880 can be replaced with a staticplate or sheet, however, as mentioned previously, a roller is preferredsince a static plate or sheet can induce strain on the nonwoven causingnecking.

From the second pivot roller 880, the first nonwoven 844 can be made toproceed to a second series of rollers 883. The second series of rollers883 are arranged relative to the second pivot roller 880 such that theangle 885 between first nonwoven 844 approaching the second pivot roller880 and the first nonwoven 844 departing the second pivot roller 880ranges from 0 degrees to 90 degrees. As shown in FIG. 8, the secondseries of rollers 883 directs the first nonwoven 844 first away from thesecond pivot roller 880 and then back to the second roller 832 formingthe first nip 834 along a path which passes the first bonding surface843 beneath the second pivot roller 880 so that any strands expelledfrom the first bonding surface 843 at the second pivot roller 880 can berecollected onto the first bonding surface 843 prior to reaching thesecond roller 832. The second series of rollers 883 can also be arrangedto direct the first nonwoven 844 to a first adhesive applicator 842applying an adhesive to the first bonding surface 843 prior to passingbeneath the second pivot roller 880.

Forcing the first bonding surface 843 of the first nonwoven 844 to makecontact with the cooled surface 812 of the drum 810 in the secondquadrant 811 b has other advantages such as enabling the apparatus toautomatically thread itself during initial startup. During initialstartup, the elastomeric strands 823 are not heavy enough toautomatically separate from the cooled surface 812 of the drum 810 andtransfer to the first roller 830. As a result, the elastomeric strands823 stick to the cooled surface 812 of the drum 810, bypassing the firstroller 830 in the third quadrant 811 c. By forcing the first bondingsurface 843 into contact with the cooled surface 812 of the drum 810 inthe second quadrant 811 b, the elastomeric strands 823 are removed fromthe cooled surface 812 of the drum 810 and redirected to the first nip834 formed between the first and second rollers 830, 832, respectively.

An elastomeric nonwoven laminate produced using any apparatus and methodof the present invention disclosed herein with regard to FIGS. 3, 7, and8, is illustrated in FIGS. 9 a and 9 b. Note that with regard to FIG. 3,a first adhesive 941 is not present.

FIG. 9 a shows, in exaggerated form, the corrugation of the first andsecond nonwovens 944, 924, respectively with corrugation hills 928 andcorrugation valleys 929 that occur after the first and second nonwovens944, 924 are joined to the elastomeric strands 923. Corrugation is usedto describe irregular corrugation hills 928 and corrugation valleys 929that alternate. As shown, the first and second nonwovens 944, 924 arecorrugated in the cross direction 945 with the corrugation hills 928 andcorrugation valleys 929 alternating in the machine direction 940. Once astrain is placed on the elastomeric laminate 990 in the machinedirection 940, the corrugations enable the first and second nonwovens944, 924 to extend with the plurality of elastomeric strands 923 atleast to the point of reaching the force wall, which is about where thecorrugations flatten out. As the strain is removed, the plurality ofelastomeric strands 923 contracts back toward their original, relaxedlength. This contraction causes the observed first and second nonwoven944, 924 corrugations.

Strain is measured as the percent of length increase in the plurality ofelastomeric strands 923 under load. For example, a strand with a freeand stretchable strand length of 15 centimeters (cm) may have a loadapplied such that the 15 cm strand elastomeric is now 18 cm long. Thislength increase of 3 cm is 20% of 15 cm ( 3/15), or a 20% strain. Theelastomeric nonwoven 990 produced according to the present invention mayhave a strain ranging from about 20% to about 500%, preferably fromabout 100% to about 400%, and more preferably from about 200% to about400%.

Since the primary function of the elastomeric nonwoven laminate is to bestretchable, the elastomeric nonwoven laminate is capable of at least a50% strain prior to reaching the force wall. Although the force wall hasgenerally been described as the point where the corrugations nearlyflatten out, the force wall typically occurs when the force required fora 10% increase in strain increases at least about 20%. Depending upondesign choice and the particular application of the elastomeric nonwovenlaminate, the elastomeric nonwoven laminate can be made to endure astrain greater than 50%, 100%, 200%, or 300% prior to reaching the forcewall. Preferably, the elastomeric nonwoven laminate produced accordingto the present invention is capable of at least a 100% strain prior toreaching the force wall. More preferably, the elastomeric nonwovenlaminate is capable of at least a 200% strain prior to reaching theforce wall.

The first nonwoven and the second nonwoven may comprise any nonwovenmaterial known in the art. The first nonwoven and the second nonwovenmay comprise fibers made of polypropylene, polyethylene, polyester,nylon, cellulose, polyamide, or combinations of such materials. Fibersof one material or fibers of different materials or materialcombinations may be used in the first and/or second nonwoven.

Any process known in the art may be used to make the first nonwovenand/or the second nonwoven. Exemplary processes include spunbond,spunbond meltblown spunbond (SMS), spunbond meltblown meltblown spunbond(SMMS), carded and the like. Particularly acceptable nonwovens includehigh elongation carded (HEC) nonwovens and deep activation polypropylene(DAPP) nonwovens.

The first nonwoven and the second nonwoven may comprise fibers that arebonded internally, including fibers that are needle punched, hydroentangled, spun bonded, thermally bonded, bonded by various types ofchemical bonding such as latex bonding, powder bonding, and the like.Preferably, the basis weight of the first nonwoven and/or secondnonwoven is in the range of about 10 gsm to about 30 gsm.

The elastomeric strands preferably extend in a parallel uniformly spacedarrangement between the first nonwoven and the second nonwoven. However,the elastomeric strands may be arranged in any configuration desired.For instance, the strands may be arranged to provide a specific forceprofile in the elastomeric nonwoven laminate by varying the thickness ofthe individual strands or the spacing between them.

In addition, the shape of the elastomeric strands is not limited. Forexample, typical elastomeric strands have a circular cross sectionalshape, but sometimes the plurality of elastomeric strands may havedifferent shapes, such as a trilobal shape, or a flat (i.e., “ribbon”like) shape. Further, the thickness or diameter of the elastomericstrands 23 may vary in order to accommodate a particular application.

The plurality of elastomeric strands is preferably made of a resilientlyelastic thermoplastic material. The elastomeric strands may be made fromliquid elastomeric that can be extruded through a die to achieve adesired strand elastomeric diameter and/or shape. The elastomericstrands are preferably styrene block copolymers, polyurethane or latexrubber having a diameter ranging between about 0.15 mm and about 0.5 mmand a density ranging from about 600 kg/m³ to about 1250 kg/m³.

Although the first nonwoven, second nonwoven and plurality ofelastomeric strands have been described as adhesively bonded, they maybe joined by any joining means known in the art. Some examples ofsuitable joining means and/or methods for joining include, but are notlimited to, adhesives, cohesives, thermal bonding, pressure bonding,mechanical bonds, ultrasonic bonding, radio frequency bonds and/or anycombination of any known methods of joining such materials.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

All documents cited in the Detailed Description of the Invention are, inrelevant part, incorporated herein by reference; the citation of anydocument is not to be construed as an admission that it is prior artwith respect to the present invention. To the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

1. A method for making an elastomeric nonwoven laminate from a pluralityof elastomeric strands and a nonwoven layer, the method comprising: a.providing an apparatus comprising i. a drum having a cooled surfacerotating about an axis and having a surface speed V₁, the drum having anupper half and a lower half; ii. an extruder extruding a plurality ofmolten streams of polymer onto the cooled surface of the upper half ofthe drum at a point of extrusion to form a plurality of elastomericstrands; iii. a transferring device positioned proximate to the cooledsurface of the drum, the transferring device having a surface speed V2which is greater than the surface speed V1 of the drum, whereby the drumtransfers the plurality of elastomeric strands to the transferringdevice wherein the span of unsupported strands between the cooledsurface of the drum and the transferring device is between about 10 mmand about 200 mm to provide a controlled distribution of elastomericstrands entering the transferring device; iv. a first nonwoven sourcesupplying a first nonwoven web to the transferring device; v. anadhesive source for applying adhesive in advance of the transferringdevice; and b. joining the plurality of elastomeric strands to the firstnonwoven web at a point of lamination thereby forming a nonwovenelastomeric laminate wherein at least two adjacent strands of theelastomeric laminate are separated by a distance of between about 1 mmand about 3 mm.
 2. The method of claim 1, wherein the apparatus includesa startup device disposed adjacent to the drum downstream of theextruder adaptable for engaging or disengaging the cooled surface of thedrum such that when the startup device engages the cooled surface of thedrum, the plurality of elastomeric strands travel along the cooledsurface of the drum at the surface speed V₁ of the drum.
 3. The methodof claim 1, wherein the apparatus includes a scraper engaged with thestartup device such that the elastomeric strands are precluded fromwinding around the startup device.
 4. The method of claim 1, wherein theapparatus includes a scraper positioned adjacent to the cooled surfaceof the drum and adjacent the transferring device, the scraper beingadaptable for engaging the cooled surface of the drum so that thescraper removes elastomeric strands from the cooled surface of the drumthat inadvertently fail to transfer to the transferring device.
 5. Themethod of claim 1, wherein the apparatus includes a deflector devicedisposed adjacent to the cooled surface of the drum such that snap backdistances of broken strands are minimized.
 6. The method of claim 1,wherein the transferring device comprises a roller positioned proximateto the cooled surface of the drum, wherein the first nonwoven istensioned such that the first bonding surface contacts the rollerthereby creating a nip force to form the elastomeric nonwoven laminate.7. The method of claim 1, wherein the span of unsupported strandsbetween the cooled surface of the drum and the transferring device isbetween about 20 mm and about 50 mm.
 8. The method of claim 1, whereinthe apparatus includes a second nonwoven web source supplying a secondnonwoven to the transferring device, wherein the first and nonwoven websare joined in a face-to-face arrangement at the transferring devicesandwiching the plurality of elastomeric strands therebetween.
 9. Themethod of claim 8, wherein the apparatus includes a second adhesivesource located between the second nonwoven source and the transferringdevice for applying adhesive to the second nonwoven web in advance ofreaching the transferring device.
 10. The method of claim 1, wherein afirst bonding surface of the first nonwoven is directed to make contactwith the cooled surface of the drum so that the first bonding surfaceremoves strands from the cooled surface of the drum that inadvertentlyfail to transfer to the transferring device and wherein a secondnonwoven source supplies a second nonwoven having a second bondingsurface to the transferring device, wherein the adhesive source appliesadhesive to the second bonding surface in advance of the transferringdevice such that the second nonwoven can be bonded to the firstnonwoven.
 11. The method of claim 1 wherein the elastomeric strands arestrained when the strands are joined to the first nonwoven web.
 12. Themethod of claim 11 further comprising the step of allowing the resultingelastomeric laminate to relax at least partially after the elastomericstrands are joined to the first nonwoven web thereby causing theformation of corrugations on the elastomeric laminate.
 13. The method ofclaim 12 wherein the first nonwoven web has a basis weight of betweenabout 10 gsm and about 30 gsm.
 14. The method of claim 8 wherein theelastomeric strands are strained when the strands are joined to thefirst and second nonwoven webs.
 15. The method of claim 14 furthercomprising the step of allowing the resulting elastomeric laminate torelax at least partially after the elastomeric strands are joined to thefirst and second nonwoven webs thereby causing the formation ofcorrugations on the elastomeric laminate.
 16. The method of claim 15wherein the second nonwoven web has a basis weight of between about 10gsm and about 30 gsm.
 17. The method of claim 1 wherein the distancebetween two adjacent stands is not the same as the distance between twoother adjacent strands of the elastomeric laminate.
 18. The method ofclaim 1 wherein an elastomeric strand of the elastomeric laminate has adiameter of between about 0.15 mm and about 0.5 mm.
 19. The method ofclaim 12 wherein the elastomeric laminate has a strain of between about20% and about 500%.
 20. The method of claim 15 wherein the first andsecond nonwoven webs comprise fibers chosen from at least one ofspunbond fibers, and carded fibers and wherein the fibers of the firstand second nonwoven webs are made of a material chosen from at least oneof polypropylene, polyethylene, polyester, nylon, cellulose, andpolyamide.
 21. A method for making an elastomeric nonwoven laminate froma plurality of elastomeric strands and a nonwoven layer, the methodcomprising: a. providing an apparatus comprising i. a drum having acooled surface rotating about an axis and having a surface speed V₁, thedrum having an upper half and a lower half; ii. an extruder extruding aplurality of molten streams of polymer onto the cooled surface of theupper half of the drum at a point of extrusion to form a plurality ofelastomeric strands; iii. a transferring device positioned proximate tothe cooled surface of the drum, the transferring device having a surfacespeed V2 which is greater than the surface speed V1 of the drum, wherebythe drum transfers the plurality of elastomeric strands to thetransferring device wherein the span of unsupported strands between thecooled surface of the drum and the transferring device is between about10 mm and about 200 mm to provide a controlled distribution ofelastomeric strands entering the transferring device; iv. a firstnonwoven source supplying a first nonwoven web to the transferringdevice; v. an adhesive source for applying adhesive in advance of thetransferring device; vi. a second nonwoven source supplying a secondnonwoven web; b. joining the plurality of elastomeric strands to thefirst nonwoven web at a point of lamination, wherein the elastomericstrands are strained when the strands are joined to the first nonwovenweb; c. joining the second nonwoven web to first nonwoven web such thatsaid elastomeric strands are disposed between said first and secondnonwoven webs thereby forming a laminate; and d. allowing the resultinglaminate to relax at least partially such that corrugations are formedon the laminate thereby forming a nonwoven elastomeric laminate, whereinat least two adjacent strands of the elastomeric laminate are separatedby a distance of between about 1 mm and about 3 mm.